This invention relates to a method for fabricating semiconductor devices specifically a low defect device in which the deleterious effects of residual impurity products are eliminated.
In a copending application entitled "Method For Fabricating Semiconductor Devices Using Composite Mask and Ion Implanation", Ser. No. 409,903, filed Oct. 26, 1973, and now U.S. Pat. No. 3,928,081 a method is disclosed where by using an initial composite mask, misalignment tolerances can be eliminated to permit fabrication of devices having a smaller geometry. The copending application dopes the various openings exposed by the composite mask by selectively covering these openings with either a photoresist or some metal such as aluminum; in other words, a material is easily removed. In some cases utilizing the foregoing technique semiconductor body contamination may be introduced producing defect regions; for example regions where unwanted materials might be diffused inwardly.